Machine tool control apparatus



Aug. 7, 1945. R, RODAL MACHINE TOOL CONTROL APPARATUS Filed April 26, 1945 12 Sheets-Sheet 1 321. gy Q Aug. 7, 1945.

R. RO DAL MACHINE TOO L CONTROL APPARATUS Filed April 26,- 1943 12 Sheets-Shed 2 Aug. 7, 1945. R. RoDAL I 2,381,312 MACHINE TOOL CONTROL APPARATUS v Filed April 26, 1943 12 Sheets-Sheet 3 l2 Sheets-Sheet 4 "RTE %1.

R. RODAL Filed April 26, 1945 EQ= whi MACHINE TOOL CONTROL APPARATUS Aug. 7, 1945.

Q4 I %Z Aug. 7, 1945. R. RODAL 2,381,312

MACHINE TOOL CONTROL APPARATUS Filed April 26,1945 12 Sheets-Sheet 5 Aug, 7, 1945.

R. RODAL MACHINE TOOL CONTROL APPARATUS Filed Afiril 26, 1945 12 sheets-sheet e R. RODAL 2,381,312

MACHINE TOOL CONTROL APPARATUS Aug. 7, 1945 I Filed A ril 26, 1945 12- Sheets-Sheet 7 Aug. 7, 1 945.

R. RODAL MACI IINE TOOL CONTROL APPARATUS Filed April 26, 1945 12 Sheets-Sheet 8 Aug. 7, 1945. R. RODAL 2,381,312

MACHINE TOOL CONTROL APPARATUS Filed April 26, 1945 12 Sheets-Sheet 9 ma W I f 12 Sheets-Sheet 10 R. RODAL MACHINE TOOL CONTROL APPARATUS Filed April 26, 1943 J W W,

Aug. 7, 1945.

Aug. 7, 1945. R. RODAL MACHINE TOOL CONTROL APPARATUS l2 Sheets-Sheet ll 4 eQW Filed April 26, 1945 Aug.- 7, 1945. R., RODAL 2,381,312

' MACHliNE TOOL CONTROL APPARATUS Filed April 26, 1943 l2 Sheets-Sheet 12 amm n Patented Aug. 7, 1945 UNITED STATE s PATENT OFFICE MACHINE TOOL CONTROL APPARATUS Ralph Bodal, Richmond, ma, assignor' to National Automatic Tool Company, Inc., Richmond, Ind., a corporation of Indiana Application April 2a, 1943, Serial No. 484,528

10 Claims.

My invention relates generally to machine tool control apparatus, and more particularly to improvements in hydraulic and electrical control apparatus for drilling and tapping machines.

In the use of automatic and semi-automatic drilling and tapping machines, there are frequent occasions upon which the operator finds it desirable to control the operation of the machine manually, as, for example, during the set-up of the machine, when the machine is to perform operations upon work held in fixtures which are arranged to move the work from one position to is employed.

A further object is to provide an improved hydraulic control apparatus for machine tools in which a machine cycle is completed automatically upon initiation by the operator, or the automatic control may readily be rendered ineffective and a manual servo valve apparatus utilized for controlling the machine operation.

A further object is to provide an improved servo valve mechanism for the hydraulic control of machine tools.

Other objects will appear from the following description, reference being -had to the accompanying drawings, in which:

Fig.- l is a front elevation of a machine incorporating the invention;

Fig. 2 is a side elevational view thereof;

Fig. 3 is a front elevational view of the lower portion of the machine tool to an enlarged scale;

Fig. 4 is a left-side elevational view of the knee portion of the machine;

Fig. 5 is a central vertical sectional view of .the knee portion of the machine taken on the line 5-4 of Fig.1;

Fig. 6 is a schematic diagram of the complete hydraulic system showing the parts thereof in the position assumed during a rapid forward traverse of a drilling operation;

Fig. 7 is a view similar to Fig. 6, showing theparts in the position. for the forward fed of a drilling operation;

Fig. 8 is a view similar to Fig. 6, showing the arts in position for the rapid reverse traverse of a drilling cycle;

Fig. 9 is a view similar to Fig. 6 showing the parts in the position assumed during a rapid forward traverse of a tappin cycle;

Fig. 10 is a view similar to Fig. 6, showing the parts in the position assumed during the feed forward traverse of a tapping cycle;

' Fig. 11 is a view similar to Fig. 6, showingthepositions of the parts during the reverse feed portion of the stroke of a tapping cycle;

Fig. 12 is a schematic wiring diagram of the electrical controls;

Fig. 13 is a longitudinal sectional view of the pilot control valve and associated parts;

Figs. 14 and 15 are traverse sectional views, to

an enlarged scale, taken on the lines l4li and I i-J 5 respectively of Fig. 13; and

Fig. 16 is a left-hand end elevational view of the valve shown in Fig. 13, drawn to an enlarged scale.

General description The invention is illustrated as applied to a light sensitive multiple spindle drilling and tapping machine. As shown in Figs. 1 to 5, a vertical column 20 is mounted upon or formed integrally with a. base 22 and provided with ways 24'. Mounted at the top of the column 20 is a gear chest 26 provided with a tool-driving motor 28 and a spindle skirt 30. On the-lower plate of the latter are secured adjustable spindle arms 32 for adjustably positioning spindles 34 (only one shown) which carry the cutting tools, such as the twist drill 36. v

A counterweight balanced knee 38 is slidable upon the ways 24, being elevated and lowered manually by means of a crank 40 operating through suitable gearing and an elevating screw 4| which is threaded in a suitable nut element 43 secured in the base 22. A work table 44 is supported by the upper end of a piston rod 48, the

lower end 48 of the rod being threaded and provided with an adjustable positive stop nut 50.

Hydraulic and electrical control mechanism,

hereinafter to be described, is provided for raising and lowering the work table 44 with respect This hydraulic mechanism is supplied with a suitable hydraulic pressure fluid, such as oil, by a pump unit 52 driven by a pump motor 54. The pump unit 52 is located in a reservoir housing 55 containing a drain or sump S. and is preferably of the tandem type including a high pressure small volume pump and a low pressure large volume pump provided with suitable relief and transfer valves so as to be capable of utilizing the output of both pumps when, as in rapid traverse portions of the cycle, it is desired to have large volume delivery at relatively low pressure. and to utilize only the high pressure pump when, as, for example, during the feeding portion of the cycle, a relatively small volumetric the elevation and lowering of the work table; a

foot switch lever 66, which, when tilted to the valve is normally urged to the right (Fig. 6) by a compression coil spring H and is moved to the left by the oil pressure, thereby controlling the effective size of an aperture I" formed therein. The governor valve thus maintains the pressure in the chamber I03.2 substantially constant so that the feed adjusting valve I02 will be capable of metering the oil flow accurately.

Oil may flow to the governing valve I04 through a passageway H8, which communicates, through the feed valve cylinder H0.I, with a passageway I I0.2, the latter intersecting the bore for the tapdrill selector valve I08. The passageway H82 terminates in a groove H8.3 surrounding the directional valve -I I2, When the feed valve I08 is in the position shown in Fig. 6, its cylinder H81 is in communication with the sump through a duct ms.

right, may be used to initiate the forward (upward) portion of an automatic cycle of operation,

and which, when tilted to the left, causes emergency reverse (downward) movement of the work table; a tap-drill selector valve knob 00, by which the character of the automatic operating cycle, whether drilling or tapping, may be determined; a feed rate adjusting valve knob I0, by which the rate of upward teed during an auto- Y matic drilling cycle, and both upward and downward feed during an automatic tapping cycle, are controlled; a start push button 12; a stop" push button I4; and in such instances as the machine is designed to be used for step drilling and through drilling, a "step-through drill" push button I5. Various elements of the electrical control system are mounted within a cabinet lssecured at the rear of the vertical column 20.

Rigidly secured to the table 44 is a feed dog bracket 80 (Fig. 4) to which a dog BI is secured in adjusted position for cooperation with a feed. valve lever 82. A reverse wise secured to the table 44 for the support of an dog bracket 84 is likeadjustable dog 85 cooperable with a reverse lever 86, by which a reverse or limit switch 01 is operated.

A rack 88 is secured to the table 44 and through a train of gearing, including gear 89, pinion 90, and gear 3|, drives a servo valve sleeve 02 (Fig. 13).-

A pair of guide rods 94 (Fig. 3) are rigidly secured to the table 44 and extend through suitable guide bearings formed in the knee 38.

The hydraulic control valves are illustrated diagrammatically in Figs. 6 in a valve body I00, and, as shown in Fig. 6, comprise a feed adjusting valve I02, 2. pressure governing valve I04, a feed valve I00, a tap-drill selector valve I08, a spool valve H0, a directional valve H2, and a manual servo valve H4, which cooperates with its follower sleeve 92.

Components of hydraulic controls The feed adjusting valve I02 has a bore I028,

to 12 as being'mounted V The tap-drill selector valve I08, when in the position shown, connects a passageway IS with a duct I22, and when in its other position (90 counterclockwise from the position shown) connects the passageway 0.2 with the passageway I22. The passageway I22 leads to a groove I221 surrounding the directional valve H2 (Figs. 6 and 8). I

The discharge from the pump 52 is supplied through a conduit I24 which leads to an annulus I24.I surrounding a portion of the spool valve (it. A passageway I208 leads to the sump from the annularspace I2 6.I S surrounding the spool valve I I0. The spool valve H0 is normally urged to the right (Fig. 6) by a' compression coil spring I28, and is operable by a rack I28 meshing with a pinion I3I. The pinion I3I is adapted to be rotated clockwise upon energization of a solenoid I33. When the spool valve H0 is in the position shown in Fig. 6, the annulus I26.I is in communication with a duct I30 leading to the space IBM at the right-hand end of the cylinder for the directional valve H2, while the annulus 0261s communicates through a duct I32 with a space I32.I at the left-hand end of the, cylinder for the directional valve H2. When the solenoid I33 t is deenergized, and the valve H0 moved'to the right, these connections are reversed,- since the valve H0 has its bore communicating with the space I20.IS through a port III (Fig. 6).

, A passageway I 34 connects annular groove I321 surrounding directional valve 1 I2 with an annular groove I34.2 formedin the sleeve 02, the passageway I34 being connected to the pump 52 by a conduit I343. A -passageway I38 connects a groove I36.I of the directional valve with a groove 326.2 formed in the external surface of the sleeve A duct I38 connects an annular groove I321 around the directional valve H2 with an annular groove I301 formed around the sleeve 92. A conduit I40 connects a groove I40.I around the .sleeve 92 with the space 0.2 at the lower end of actuating cylinder I42, while a conduit I44 connects a groove I44.I around the sleeve 92 with the upper end I44.2 of the cylinder I42.

The upper end of the piston rod 48, to which the piston I46 is secured, is of smaller diameter than the lower end portion thereof, for a purpose which will hereinafter be apparent.

The servo valve lever 04 is pivoted to the end of the servo valve H4 by a pin I40 and has an end portion I49 forming a fulcrum pivot in a slot I50 formed in a guide I52. The valve II4 may thus be moved longitudinally orrotated relative to its sleeve 02. The valve I I4 is held in the longitudinal position to which it may be adjusted by a pair of spring-pressed detent balls I64 'cooperable in either of a pair of grooves I66 formed within the sleeve 92. j

The servo valve II4 has an axially drilled hole I998 (Figs. 13 to 16) and is provided with an open end slot I60 cooperable with an equalizer blade I62 when the servo valve H4 is moved to the left (Fig. 13). The equalizer blade I62 fits in slots I61 milled in the end of sleeve 92.

As best shown in Fig. 16, the equalizer blade, and

hence also the servo valve II4--when the latter is in its inner or operative positionare held in predetermined angular position with respect to the sleeve 92 by four spring-pressed pins I64. Each of the pins I64 has a head I66 which rests against-a shoulder I69, being pressed thereagainst by a compression spring I10, the outer end of which is seated in a hollowset screw I12. Thus.

the extent of rotary movement of the servo valve. II4 with respect to its sleeve 92 is limited by the .by flats on the valve II4, these spaces communi cating with an annular space I16.|, which is nor- 'mally in communication with the annular groove I 34.2. Similarly, there are passageways I19 spaced 90 with reference to the passageways I15.I and communicating with annular groove latter is normally in communication with the groove I34.4 around the sleeve 92. Theequalizer blade I62 is held in position by a wall I19 forming part of the valve housing. Electrical control circuits The electrical system is illustrated in the diagram of Fig. 12 as being supplied with three phase current from ally operated main switch I90 connected to line conductors LI, L2, and L3. The conductors LI, L2, and L3 lead to the starting box I92 for the pump motor 54 and to the starting box I94 for the tool driving motor 29. The control circuits comprise a switch I96 operated by the "stop push button 14 and a switch I98 operated by the start push button 12. The stop" switch I96, which is normally closed, connects line conductor L3 with a conductor I 99." The start" switch I99 is adapted to connect this conductor I99 with a conductor 200. A relay device 202 has one end of its-winding connected to the conductor 200 and the other end thereof connected to a return conductor 204,

which returns to line LI through overload switches 206, 201, and 208, which open in the usual manner upon an overload upon the tool driving motor 29 in the forward or reverse direction or due to an overload upon the pump motor 64.

Energization of the relay' 202, in addition to initiating the operation of the pump startin mechanism I92, closes a, switch 209, which establishes a holding circuitbetween conductors I99 and 200, thus permitting release of the start push button 12.

The forward and reverse-treadle 66 is adapted to operate a forward switch 2I0, which normally connects the conductor 200 with a conductor 2 I2 mm, which v a suitable source through a manu-- and causes the switch to complete a circuit between the conductor 200 and a conductor 2 I4. The conductor 2I4 connects through the limit switch 91 with a relay winding CR2 and with the winding of the solenoid I 33 through a conductor 2 I 6. The other terminals of the winding of relay CR2 and of the solenoid I33 are connected to the line conductor LI -When the forward-reverse treadle 66 is swung counterclockwise (as when it is desired to reverse the direction of the travel of the table in an emergency), a normally closed reverse switch 2I9 is opened, disconnecting a conductor 220 from the conductor 200.

The relay CR2, when energized, opens a switch 222 and closes a switch 223, the latter being,

adapted to make connection between the conductors 220 and 2", while the switch 222 is adapted to make connection between a conductor 2 I2 and a conductor 224.

' When the tap-drill selector knob '69 is in "drill" position, a switch 226 is closed and a switch 228 open, while when this knob 69 is turned to tap position, the switch 229 is closed, and the switch 226 is open. The switch 226, when closed, connects the conductor 200 with a conductor 230,'the

latter leading to the winding of a "forward relay 232 forming part of the actuating mechanism for the starting box I94 of the tool driving motor 29.

When the switch 229 is closed, a circuit is completed from the conductor 200 throughthe wind-' ing of a relay CRI to the line LI. I When the relay CRI is energized, it closes switches 234 and 235, the switch 234, when closed, connecting the conductor 224 with a reverse relay 236 forming part of the starting box I94 of the tool driving motor 29. The switch 235, when closed; establishes a connection between conductors 2I6' and 230. 5

Operation through a drilling cycle Assuming that the work has been set up on the table 44 and the tools properly set relative thereto, a drilling operation is commenced by pressing the start push button 12, temporarily closing circuit which connects the conductor 200 to line L3 through the stop" switch I96. The energiza-- tion of the relay 202 also causes the starting box l92 to operate to start the pump motor 54, thereby supplying the hydraulic actuating fluid (oil) to the hydraulic system. Since the switch 226- is closed, the relay 232 will be energized through the conductor 230 and cause the tool driving motor 28 to rotate in a forward direction.

The operator then steps on the right-hand portion of the treadle switchactuator 66. swinging the latter clockwise, and moving the "forward switch 2I0 downwardly (Fig. 12) to connect the conductor 214 to the conductor 200 for a short interval of time. During this interval. the relay CR2 is energized through the circuit including the limit switch 81, thereby to open switch 222 and close switch 223. Closureof the switch 223 estab-. l shes a holding circuit for the relay'CR2 through the "reverse switch 2I8, conductor 220. switch relay 236 due to inadvertent movement of the. tap-drill knob 68 to tap position The completion of the circuit to the conducto 2I4 also results in energization of th'e "forward" solenoid I33, which, as shown in Fig. 6, moves the rack I28 inwardly (to the left), whereby the oil pressure in conduit I24 flows past the spool valve annulus I24.I into conduit I 30, to the space I30.I at the right-hand end of the cylinder for the directional valve II2, moving the latter to the left, as shown in Fig. 6. When in this position, oil under pressure may flow through the conduit I34.3, passageway I34, annular space I34.I, annular groove I38. I passageway I38,annular groove I38.I in the sleeve of the servo valve, and hence around the latter to the annular groove I40.I and conduit I40 to the lower end I40.2 of the actuating cylinder I42, forcing the piston I48 and hence the table 44 upwardly. The oil above the piston I48 escapes through conduit I44 to the groove I44. I around the servo valve sleeve 82, across the servo valve to groove I362, through passageway I38, across the directional valve II2 to groove 8.3, and hence through passageway 8.2 to tho annular space II8.I around the feed valve I08, to the passageway I I8S.

It will be noted that the flow of oil from the upper end of the actuating cylinder is unrestricted and the table will thus be elevated rapidly to the position at which the tools are about to engage the work pieces. When the table arrives at this position, the feed dog 8I engages the roller on the feed valve lever 82 and the latter presses the feed valve I08 inwardly to the position in which it is shown in Fig. '7.

Under these circumstances, the supply of oil to the lower end of the cylinder is through the same hydraulic circuit as previously described, but the oil forced from the top of the actuating cylinder I 42 can no longer escape to the sump through the passageway IISS, but instead, must flow through the passageway II8, through the re- ,stricted passageway I in the governor valve I 04, and hence through passageway I03.I through the flow metering groove I03 of the feed adjusting valve I02 to the sump. The setting of the valve I02 is such as to secure the proper feed rate for the particular machining operation to be performed. The hydraulic circuit during the feeding portion of the cycle is indicated by the arrows in Fig. '7.

When the table has been elevated to the position at which the tools have completed their operations upon the work, the dog 85 (Fig. 4) engages the roller at the end of the limit switch arm 88-, and opens the limit switch 81 (Fig. 12) Opening of the switch 8'! results in deenergization of the relay CR2 and the solenoid I33. Deenergization of the control relay CR2 results in opening the switch 223 which was in the holding circuit for this relay so that upon subsequent closure of the limit switch 81, the relay CR2 will not be reenergized.

Deenergization of the solenoid I33 permits spring I28 to expand and move the spool valve II 0 I to the right, as shown in Figs. 8 and 12. Under these conditions, oil under pressure supplied this position, oil under pressure may flow from the a conduit I34.3 to the passageway I 34, around the space I34.I of the directional valve I I2, through the annulus I38.I, passageway I38, and groove I38.2, across the servo valve II4, to the annular groove I44.l, and hence through conduit I44 to the space I44.2 at the upper end of the actua ing cylinder I42. Pressure is thu exerted above the piston I48 and commences forcing the latter downwardly, the oil escaping from the lower end 02 of the actuating cylinder through conduit I40, annular groove I40.I, across the servo valve II 4, to the groove I38.2 in the servo valve sleeve, passageway I38, to annular groove I38.I. The oil flows across the directional'valve II2 to annular groove I22.I and passageway I 22, through the tapdrill selector valve I08, and is discharged to the sump through duct I208.

Since the last described hydraulic path does not afford any appreciable restriction to the flow of oil, the reverse traverse will be at a rapid rate, and such downward'movement of the table 44 will continue until the piston I48 strikes the bottom of the cylinder I42. The machine tool is then in condition for a second cycle of operation.

Operation through a topping qvcle When the machine is to perform a. tapp n operation, the tap-drill knob 88 is moved to tap position, thereby rotating th'e tap-drill valve I08 to the position in which it is shown in Fig. 9, closing switch 228 (Fig. 12) and opening switch 228. Closure of the switch 228 results in energization of the relay CRI, which is connected between the switch 228 and line LI. Opening of the switch 228 results in opening of the circuit by which the "forward relay 232 of the tool driving motor starter I84 was formerly completed. The closure of the switch 234 by the relay CRI results in energize.- tion of the reverse relay 238 of the starting mechanism I84.

Upon stepping upon the right-side of the treadle 88, the forward switch 2| 0 is moved from full-line to dotted-line position, thereby completing the circuit through relay CR2 and forward solenoid I33, as previously decribed. A holding circuit for the relay CR2 is established, and at the same time, the "reverse relay 238 of the starting mechanism I94 is deenergized by the opening of a switch 222. Instead, the forward relay of the starting mechanism I84 is again energ'ized through a circuit traced as follows: From conductor 200 through switch 2I0, limit switch 81,-conductor 2I8, switch 235, conductor 230, relay 232, and through conductor 204 to line LI.

Energization of the solenoid I33 results in shifting the spool valve I I0 to the left (Fig. 9) against the force of its spring I28, whereupon, oil will flow from the pump 82 through conduit I24 to the annular space I J around the spool valve H0, .and hence through passageway I30 to the space I30.I at the right-hand end of the directional valve II2, the oil in the space I32.I at the other end of the spool valve being discharged through the passageway I32 and space I 28.I S to the sump, all as indicated by the arrows.

Oil under pressure in theconduit I34.3 may then flow through the passageway I34 and an annular'space I34.I around the directional valve through the annular groove I38.I and passageway I38 to annular groove I382 and hence across the servo valve II4 through annular groove I40.I and conduit I40 to the space 0.2 at the bottom of the actuating cylinder I42, exerting a pressure upon the lower face of the piston I48 and causing upward movement thereof. The oil in the space 4.2 at the upper end of the actuating cylinder is discharged through conduit I44 to annular groove I44.I across servo valve II4 to annular groove I382 and passageway I38 to anlay 232.

around the directional valve to passageway 8.2 through the space-I I8.I around the feed valve 106 and hence through the passageway H88 to the m a After the table has thus raised the work to position for engagement by the taps, the dog 8I engages the roller of the feedvvalve lever 82 and the latter presses the feed valve I86 inwardly to cut ofl'communication between the space MBA and the passageway I I8S. This condition is'illus- J trated in Fig. 10, in which the hydraulic-flow is from the pump 52 through the conduit I24 and :through the valve mechanism, .as reviously descrlbed with reference to Fig. 9, to the lower end 140.2 of the actuating cylinder. The oil from the upper end 4.2 of the cylinder I42 is, however, discharged at a controlled rate, since the valve I06 has cut of! the free discharge of the oil from the space II8.I to the passageway H88 and instead, the oil must flow through the duct I I8, around the governor valve I04, through the passageway I03.I and through the feed adjusting metering -valve ,The taps are of the floating type, that is',,the tool spindles are arranged to slide longitudinally relative to their'driving shafts, being resiliently held intheir uppermost position. The feed adjusting valve I02 is adjusted to a position such that the rate of upward feed of the table is somewhat slower than the rate at which the taps cut into the work. Thus, during the upward feed of the work, the taps are drawn downwardly by virtue of the fact that the tapping tools are feeding themselves into the work at a slightly faster rate than the work is being moved upwardly.

. 1 2,831,812 nular groove I86.I. The oil continues flowing tor valve I08, to passageway 82, through the feed valve space II8.I and duct II8, through the governor. valve I04, and hence through the feed adjusting valve I02.

Sdnce' the position of the feed adjusting valve is not changed during a tapping cycle, the rate of discharge of oil during the downwardfeed of the tablewill be the same as during the upward feed. However, dueqto the fact that the portion of the piston rod 46 above the piston is of lesser Y diameter than the portion below the piston, there will be a lesser volume of oildisplaced by the'pis .ton rod per inch of downward teed than was displaced during th upward ieed of the table. I Thus, the downward feed will be more rapid than the upward feed and will be at substantially-the rate at which the taps feed themselves out of the work piece. Thus, the taps may float" during the downward feed of the table as well as during the upward feed. v

Whenthe table reaches the position at which the taps have'been completely disengaged from the work, the feed valve dog 8I permits the feed valve lever 82 to return to normal, whereupon,

the feed valve vI06 is forced outwardly by its spring and the oilfrom the lower end I 40.2 oi? the actuating cylinder I42, instead of being forced through the governor valve I04 and feed adJusting valve I02, may escape through the, passageway IISS, thereby permitting the rapid traverse of the table to its lowermost position, in which position it is arrested by engagement of the 7 piston I46 with the lower end of the cylinder I42.

In both the drilling and tapping operations, the stop nut 50 is adjusted on the lower end of the piston rod 46 so as to limit the upward move- When the work piece has been tapped to proper stopped and then position by its spring I28 and the hydraulic fluid supplied by the pump 52 is thus forced from the conduit I24 through the space I 24.I around the spool valve, through the passageway I32, to the space I32.I at the left-hand end of the directional valve 2, thus forcing the latter to the'right. The oil in its space I30.I atthe other end of the directional valve II2 flows through the passageway I30 and through the bore of the spool valve H0 and ports III to'the passageway I26S, as indicated by the arrows.

With the directional valve I I2 in its right-most position, oil under pressure flows ,fromthe conduit I34.3, passageway I34, through the space I34.I around the directional valve, annular groove I36.I passageway I36, annular groove I36.2, around the servo valve II4, annular groove I44.I, conduit I44, to the upper'end 4.2 of actuating cylinder I42, causing downward movement of the 'ment of the table and prevent damage should the limit switch, andithe parts controlled thereby, fail tooperate with sufllcient rapidity.

Operation using servo valve Whenever it is desired to drill or-tap using a manual control, or whenever it is desired to move the table to a different position, as when setting up the machine and making adjustments inthe positions of the dogs, the movement of the table may be controlled by means of the servo valve lever 64. To render the servo valve operative, the lever is swung, to the left to cause engagement of its slot I60 with the equalizing blade I62, as

shown in Fig. 13. When the servo valve I I4 is in this position; it will be noted that the lands thereof completely block'flow from the grooves I38.2 and 136.2 and when the valve is'in central rotary position, communication to the grooves I40.I and l4 4.I'is also blocked. The space I16 is; however, in communication with the pressure side of the pump through conduit I34.3, passageway I34, and groove I34.2, while the space I18 is similarly incommunication with the pressure side of the pump through conduit I34. 3 and groove Thereafter, the table may be elevated by swing- .ing the servo valve lever 64 upwardly and may be lowered by swinging this lever downwardly,

When the valve'lever64 is swung upwardly, the

spaces I16 come into registry with the ports I40.3

leading to groove I40.I (Fig. 14 andthus a path for flow of oil from the groove I 34.2. to the table. The oil in the lower end I 40.2 of the cylinder I42 flows through conduit I40, across the servo valve 4', to passageway I38, past the directional valve II2 from groove I38.I to groove I22.l. passageway I22, through the tap-drill selecgroove I40.I is established and oil may now to the lower end 0.2 of the actuating cylinder I42.

At the same time, the spaces I15.I come into reg-- istry with the ports l44.3 leading to groove I44.I,

and thus establish'apath for the flow of oil from the conduit I44, and hence from the space 4.2

atthe up er end of the actuating cylinder 14:,

to the drilled holes I163, from whence the oil may flow through the bore I588 to the sump.

Thus, oil under pressure is applied to the lower face of the piston I49 and oil permitted to escape to the sump from abovethe piston, and the piston and table move upwardly. The rate at which this fiow takes place depends upon how quickly the lever 64 is swung upwardly. However, as the table moves upwardly, the rack 98 moves with it, and thus rotates the gear 89 and pinion 90 clockwise (Figs. 14 to 16), and consequently, rotates the pinion 9| and servo valve sleeve 92 counterclockwise. Assuming that the operator held the servo valve handle 64 stationary, such counterclockwise movement of the sleeve 92 results in the servo valve H4 and its sleeve 92 again resumes the relative positions in which they are shown in Figs. 14 and 15. In this position, the spaces I16 and I18, as well as the spaces I'I4.I and I15.I are cut off from communication with the ports leading to the grooves I40.I and I44.I, and hence there can be no oil flow to or from the actuating cylinder I42.

Conversely, when the servo valve lever 64 is swung downwardly to move the servo valve 4 clockwise (Figs. 14 to 16), the spaces I19 are brought into communication with the ports of the groove I14, while the spaces I'I4.I are brought into communication with the ports leading to the groove I40.I. As a result, oil under pressure flows through the spaces I18 into the conduit I44 and from the conduit I49 through the spaces II4.I, ports I 14S, and bore I588, to the sump. Thus, the piston '46 and table 44 are moved downwardly, which, through the rack and pinion drive, causes rotation of the servo valve sleeve 92 in a clockwise direction. Such motion of the table continues until the servo valve H4 and its sleeve 92 again attain the relative positions in which they are shown in Figs, 14 to 16, at which time, the flow to and from the actuating cylinder I42- is cut off.

Relative rotation between the servo valve H4 and its sleeve 92 is limited because of the engagement of the servo valve with the equalizer blade I62, the latter being resiliently held in a central position in the slot I61 by the four spring-pressed plungers I64, and these plungers, acting through the equalizing blade, return the servo valve to neutral position relative to its sleeve 92 whenever the handle 64 is released.

When the servo valve H4 is in its operative position, and as shown in Fig. 13, it will be clear that the positions of the directional valve, the feed valve, the feed adjusting valve, and the spool valve, is immaterial, since these valves can have no effect upon the operation of the machine.

Therefore, if it is desired to perform a drilling operation using the servo valve manual control, it is necessary merely to set the tap-drill control knob 68V to drill position so as to secure forward rotation of the tool driving motor 29. Thereafter, upon pressing the start button I2, the machine may be operated through a drilling cycle by merely swinging the servo valve lever 64 upwardly at an angular velocity corresponding to the desired rates of traverse and feed, and after the work piece has been drilled to the required I depth, the work table may be lowered .at a rapid or slow rate merely by correspondingly swinging the servo valve lever 64 downwardly until the work table is low enough to permit the pieces to clear the tools.

The servo valve lever 64 operates in the manner of a dead man" control since whenever the lever is released, the spring-pressed plungers 34 and with as exacting, if not more exacting, control than if the table were substantially weight less and it were being moved by hand.

The servo valve control is of particular utility when the machine tool is used to machine pieces mounted in tumble or sliding fixtures. In such cases, the start or length of the feeding portion of the cycle maydifier, and it therefore results in a considerable saving in time to be able to control the machine by means of the servo valve.

If at any time during the automatic operation of the machine through a drilling or a tapping cycle it should become desirable to stop the operation and lower the work piece away from the tools, it is merely necessary for the operator to step upon the left-hand end of the treadle 66, whereupon, the reverse switch 2I8 will be opened, thus opening the holding circuit for the relay CR2. Opening this circuit results in deenergization of the forward solenoid I33 so as to shift the spool valve III! to the right, thereby shifting the directional valve II2 to the right and causing flow of the oil under pressure into the upper end of the cylinder I42 and permitting flow from the lower end of this cylinder, either directly to the sump in the event that the tap-drill knob 68' is in drill position, or to the sump through the feed adjusting valve I62 if the tap-drill knob 68 is set for a tapping operation and if the dog III is in position holding the feed valve I06 in its left-most position.

While I have shown and described a particular embodimentpf my invention, it will be apparent to those skilled in the art that the invention may be embodied in many other forms. I therefore desire,'by the following claims, to include within the scope of my invention, all such modifications and variations by which substantially the same results may be obtained through the use of substantially the same or equivalent means.

I claim:

'1. In a control apparatus for a machine tool having a member moved back and forth to cause operating engagement and disengagement of the work and tools, the combination of a hydraulic motor for moving said member, control means including hydraulic passageways leading to said motor and operable to cause the machine tool to execute an automatic operating cycle, a servo valve and sleeve which when in one position relative to each other have ports forming parts of said passageways and which when in another position control the flow of hydraulic fluid from 7 9,881,812 work and tools, the combination of a hydraulic motor for moving said member, control means including hydraulic passageways leading to said motor and operable to cause the machine tool to execute an automatic. operating cycle, a servo valve and sleeve which when in a first position relative to each other have ports forming parts of said passageways and which when in a secdischarge of hydraulic fluid from said motor, a

single handle for relatively shifting said servo valve from one of said positions to the other and for operating the servo valve to control the flo'w of'hydraulic fluid to and from said motor, resilient means operative between said servo valve and said sleeve. to move said valve to closed position, and a positive driving connection between said member and said sleeve.

3. The combination set forth in claim 2 in which said resilient means is rendered effective only when said valve and sleeve arein said second position. a

4. A servo valve structure for manually controlling the position of a hydraulically operated part, comprising, a valve body, a ported sleeve rotatable in said body and having its angular position controlled by the hydraulically operated part, a longitudinally movable two-position valve having ports which in one position of the valve are cooperable with the ports in said sleeve to control the flow of hydraulic actuating fluid to and from said hydraulically operated part, and which in another position is ineffective to control such flow, and manually operable means to shift said valve between its two positions and to determine its angular position with respect to said sleeve;

5. In a control apparatus for a machine tool work and tools, the combination of a'hydraulic motor for moving said member, control means including hydraulic passageways leading to said motor and operable to cause the machine tool to execute an automatic operating cycle, a servo valve and sleeve which when in one position longitudinally relative to each other have ports forming parts of said passageways and which when in another position control the flow. of hydraulic said bore, a positive driving connection between said machine tool part and said sleeve to cause rotary motion of the latter proportional to the extent of movement of the former, a valve element rotatable within said sleeve and operable with said sleeve to control the flow through the ports thereof to and from said motor, said valve having a transverse slot at one end thereof, a handle operatively connected to said valve for rotating the latter with respect to said sleeve, means comprising an equalizing blade extending through said slot and mounted for limited movement in said sleeve, said means limiting the extent of relative rotary motion of said valve and sleeve, and resilient means opposing relative rotation of said valve and sleeve from a position intermediate those determined by said motion limiting means.

7. In a servo valve mechanism for the hydraulic controlv of a'machine tool in which the machine tool comprises ahydraulic motor having a moving part, the combination of a valve body having a. bore, a ported sleeve mounted for rotation in said bore, a positive driving connection between said machine tool part and said sleeve to cause rotary motion of the latter proportional tothe extent of movement of the former, a valve element rotatable and longitudinally reciprocable within said sleeve and operable with said sleeve having a member moved back and forth to-cause V operating engagement and disengagement of the to control the flow through the ports thereof to and from said motor; a handle, an operating connection between said handle and said valve for rotating and reciprocating the latter with respect to said sleeve, means to limit the extent of relative rotary motion between said valve and said sleeve, and means to limit the extent of reciprocatory motion of said valve.

8. The combination set forth in claim 7, in which said means limiting rotary motion between said sleeve and said valve comprises a resiliently mounted element engaging said valve and said sleeve only when 'said valve is in a predetermined position longitudinally with respect. to

said sleeve, said element being operable to move said valve to a predetermined position with respect to said sleeve whenever no external torque is applied to said valve.

9. The combination set forth in claim '7, in

ametral slots formed therein and in which said motion limiting means comprises an equalizer blade located in said slots, and resilient means are provided to hold said blade centrally in one of said'slots.

10. The combination set forth in claim '7, in which said rotary motion limiting means is rendered eflective by longitudinal movement of said valve to one position and rendered ineffective by longitudinal movement of said valve to another position.

RALPH RODAL. 

